1. Field of the Invention
The invention relates to an industrial gas operated liquid heater.
It relates more specially to such an apparatus adapted for being used for heating a process liquid, in the meaning given to this term in the engineering field, that is to say a liquid containing specific products used during a process for manufacturing or producing or transforming materials.
2. Description of the Prior Art
Installations are already known for heating a process liquid, for example the dyeing bath of an autoclave, which uses a vapor circuit. In such installations, the heating efficiency of the dyeing operation is relatively low, generally of the order of 60% with respect to the LHV, (low heat value) of the fuel, so that these installations are not entirely satisfactory from the economic point of view.
A boiler is also known, for example from DE-A-No. 2 354 906, comprising a tubular hearth or furnace a front end face of which is provided with a burner and a heat exchanger in which flow the liquid to be heated and the combustion fumes, the liquid to be heated forming a liquid sheet which encloses substantially the whole tubular hearth, except for the front end face receiving the burner.
Such a boiler, which is not intended to heat a process liquid, on the one hand, which does not state, on the other hand, if the burner which it comprises is a gas burner, does not aim at obtaining a high efficiency. It is known, in fact, that for heating systems comprising a fuel oil burner the combustion gases are not appreciably cooled so as not to reach the dew point of the fumes in order to avoid the formation of sulphuric acid likely to attack the metal walls of the apparatus, because of the presence of impurities in the fuel, whereas in systems comprising a gas burner recovery of the heat from the fumes is taken as far as possible.
Furthermore, the above referred document does not provide easy dismantling of the boiler for possible cleaning of the process liquid circuit.
To overcome these drawbacks of known installations, applicants provide an apparatus for heating a process liquid allowing a high efficiency to be obtained, not only as regards the liquid heater itself but also its application to a particular process, for example in the food industry field, or in the textile industry field while being as simple as possible to use, particularly as regards the easiness of cleaning, this factor being of particular importance when the liquid is a process liquid used in the food industry or textile industry fields.
It is a general object of the invention to provide an apparatus which allows a process liquid to be heated without intermediate heat carrying fluid and which allows the temperature of said liquid contained in a tank or in an autoclave to be raised up to values of the order of or greater than 130.degree. C., the rate or rates of temperature rise being adjustable at will depending on the desiderata of practice.
It is also an object of the invention to provide such an apparatus which, while being compact, supplies sufficient power for it to be associated with other apparatus of an industrial installation comprising the liquid heater, for example an autoclave of a dyeing or bleaching installation.
It is also an object of the invention to provide such an apparatus which, by its construction as "self contained" device, may be specifically adapted to an apparatus which it is intended to equip and in the immediate vicinity of which it may be installed.
It is finally an object of the invention to provide such an apparatus which allows the installation of which it forms part to be worked similarly to what was achieved previously for known installations, in particular without it being necessary to make particular arrangements regarding the preservation of the characteristics of the process liquids used.